KR101580349B1 - Multilayered ceramic electronic component and fabricating method thereof - Google Patents

Abstract

The present invention is a multilayer ceramic electronic component, and relates to a method of manufacturing the same, the mean diameter (D _c) is smaller than the average diameter of the inner ceramic grain active region (D _a), the thickness of the cover region within the ceramic grains covered region T _c when called, the 9um≤T _c ≤25um, characterized in that the T _c / D _c ≥55, a multilayer ceramic capacitor according to the present invention can be excellent in moisture resistance characteristics.

Description

TECHNICAL FIELD [0001] The present invention relates to a multilayer ceramic electronic component and a fabrication method thereof,

The present invention relates to a multilayer ceramic electronic component and a manufacturing method thereof.

2. Description of the Related Art In recent years, as electronic products, IT, and A / V products have become smaller and more sophisticated, there has been a demand for miniaturization and high functionality of electronic components. Accordingly, demand for multilayer ceramic electronic components is increasing. Multilayer ceramic electronic parts are widely used as components of computers and mobile phones due to their small size, high capacity, and ease of mounting.

Multilayer ceramic electronic components include capacitors, inductors, varistors, and the like. In general, multilayer ceramic capacitors, which are passive elements that are the most widely used, are required to have miniaturized, high capacity and high reliability products.

For the miniaturization and high capacity of the multilayer ceramic capacitor, it is necessary to thin the ceramic sheet and the internal electrode and to form a stable layer. As the layer becomes thinner and more stable, the volume ratio of the internal electrode of the multilayer ceramic capacitor increases and the thickness of the cover layer decreases.

As the thickness of the cover layer decreases, moisture or the like may permeate from the outside, and the moisture resistance characteristic of the multilayer ceramic capacitor may be deteriorated.

The present invention is intended to provide a multilayer ceramic part excellent in moisture resistance characteristics and a method of manufacturing the same.

One embodiment of the present invention is a ceramic body comprising: a ceramic body; An external electrode formed on an outer surface of the ceramic body; And an inner electrode laminated in the ceramic body with a ceramic layer interposed therebetween, wherein the ceramic body includes an active region from the uppermost inner electrode to the lowermost inner electrode and a cover region contacting the upper and lower sides of the active region, smaller than the average diameter (D _a) of the mean diameter (D _c) is the active region within the ceramic grains of the ceramic grains within the coverage area, when referred to the thickness of the cover region T _c, and _c 9um≤T ≤25um, Lt; RTI ID = _0.0 > _Tc / Dc < / RTI >

The average diameter (D _c ) of the ceramic grains in the cover region may be an average diameter in the thickness direction.

1.1? D _a / D _c? 4.4.

The ceramic body may comprise a dielectric material, and the dielectric material may comprise barium titanate or strontium titanate.

The number of stacked internal electrodes is 250 Or more.

The internal electrode may include at least one selected from the group consisting of nickel, palladium, and alloys thereof.

The external electrode may include at least one selected from the group consisting of nickel, a nickel alloy, and palladium.

Another aspect of the present embodiment is a ceramic body including an internal electrode laminated portion in which a plurality of internal electrodes are laminated; And an outer electrode formed on the outer surface of the ceramic body, wherein a thickness (T _c ) of each of the upper and lower cover portions, which are outside the inner electrode laminate portion, of the ceramic body is 9 to 25 μm, The ceramic grain average diameter (D _c ) of the region is smaller than the average diameter (D _a ) of the ceramic grains in the internal region of the internal electrode laminate portion, and T _c / D _c ≥55.

The inner electrode stacking portion can draw adjacent inner electrodes in opposite directions.

And the outer region may be disposed in the inner electrode stacking direction of the inner electrode laminate portion.

The average diameter (D _c ) of the ceramic grains in the outer region may be an average diameter in the thickness direction.

1.1? D _a / D _c? 4.4.

The ceramic body may comprise a dielectric material, and the dielectric material may comprise barium titanate or strontium titanate.

The number of stacked internal electrodes may be 250 or more.

The internal electrode may include at least one selected from the group consisting of nickel, palladium, and alloys thereof.

The external electrode may include at least one selected from the group consisting of nickel, a nickel alloy, and palladium.

According to another embodiment of the present invention, there is provided a method for producing a ceramic powder, comprising the steps of: providing a first ceramic powder and a second ceramic powder having an average particle size of 1.1 to 4.4 times the average particle size of the first ceramic powder; Providing first and second ceramic green sheets using the first and second ceramic powders, respectively; Forming an internal electrode on the second ceramic green sheet; Stacking the first ceramic green sheets to form an upper cover and a lower cover having a thickness of 11 to 28 탆; Depositing a second ceramic green sheet having internal electrodes on a target number of layers to form a second ceramic green laminate; And laminating the lower cover, the second ceramic green laminate, and the lower cover.

In the step of preparing the first and second ceramic powders, the first and second ceramic powders may include barium titanate powder.

In the step of forming the internal electrode, the internal electrode may be formed by printing a conductive paste.

The conductive paste may include a conductive metal, and the conductive metal may include at least one selected from the group consisting of nickel, palladium, and alloys thereof.

According to the present invention, it is possible to obtain a multilayer ceramic electronic component having excellent moisture resistance characteristics and a manufacturing method thereof.

1 is a perspective view of a multilayer ceramic electronic component according to an embodiment of the present invention.
2 is a cross-sectional view taken along the line X-X 'in Fig.
3 is an enlarged view of the Y portion in Fig.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

The embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

Furthermore, embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

The shape and the size of the elements in the drawings may be exaggerated for clarity and the same elements are denoted by the same reference numerals in the drawings.

1 is a perspective view of a multilayer ceramic electronic component according to an embodiment of the present invention. 2 is a cross-sectional view taken along line XX 'of FIG. 3 is an enlarged view of the Y portion in Fig.

1, a multilayer ceramic electronic device according to an embodiment of the present invention includes a ceramic body 10, external electrodes 21 and 22 formed on the outside of the ceramic body, internal electrodes 31, 32).

The ceramic body 10 may be a rectangular parallelepiped, and the L direction may be defined as a "longitudinal direction", the W direction as a "width direction", and the T direction as a "thickness direction". The ceramic body 10 may have both end faces S1 and S4 in the longitudinal direction, both side faces S2 and S5 in the width direction and upper and lower faces S3 and S6 in the thickness direction.

The ceramic body 10 is made of ceramics, and the ceramic may be a dielectric material having a high dielectric constant, specifically, barium titanate, strontium titanate.

The external electrodes 21 and 22 may be formed facing the external portions S1 and S4 of the ceramic body. The outer electrode may be formed to extend to a portion of the neighboring other surfaces S2, S3, S5, and S6, and the bonding strength of the outer electrode to the ceramic body may be improved.

A plating layer may be formed on the external electrode for ease of mounting. The external electrodes 21 and 22 are formed of a conductive metal and may be formed of copper, a copper alloy, nickel, a nickel alloy, silver, palladium or the like, though not limited thereto. And may contain glass to prevent penetration of the plating solution.

The external electrodes 21 and 22 may be formed on both sides S1 and S4 in the longitudinal direction of the ceramic body. At this time, the external electrodes 21 and 22 may be electrically connected to the internal electrodes 31 and 32 exposed on one surface of the ceramic body 10.

The internal electrodes 31 and 32 may be formed by laminating a ceramic layer 11 in the interior of the ceramic body 10. The internal electrodes 31 and 32 may include a conductive metal such as nickel and may be subjected to low-temperature firing. The conductive metal may include at least one selected from the group consisting of gold, silver, copper, nickel, platinum, palladium, and alloys thereof.

The internal electrode may be provided with a ceramic sintered body having a high sintering temperature such as barium titanate to increase the sintering initiation temperature. Since the sintering temperature of the internal electrode is lower than that of the ceramic, the internal electrode may be sintered before the ceramic. This may reduce the coverage of the internal electrode, which may make it difficult to implement the capacitance.

The number of stacked internal electrodes may be 250 or more. This is because the number of internal electrodes to be stacked increases with the tendency to increase the capacity of electronic components. If the number of stacked internal electrodes is less than 250, it may be difficult to realize a high capacity. In addition, the thickness of the internal electrode may be reduced for high capacity.

Referring to FIG. 2, the ceramic body 10 may be divided into an active region A and a cover region C in the thickness direction. The cover region (C) may be formed in contact with the upper and lower sides of the active region (A).

The active area A refers to a region where the internal electrodes are stacked, and may refer to a region from the topmost internal electrode 31a to the lowermost internal electrode 32a. The active area can contribute to the implementation of the capacitance.

The cover region C may mean an area from the uppermost inner electrode 31a to the upper surface S3 of the ceramic body. The coverage area does not contribute to capacity implementation.

The cover region C may be formed above and below the active region A and may be referred to as an upper cover region and a lower cover region, respectively. The upper and lower regions may be symmetrical to each other. And the thickness (T _c ) of the cover region is decreased with increasing capacity.

In the present embodiment, the thickness (T _c ) of the cover region may be 9 to 25 um after firing.

According to the high capacity trend there is a thickness of the cover region (T _c) can be reduced more and more, the invention is not more than the thickness of the cover region (T _c) 25um control the grain size of the coverage area (C) and the active region (A) So as to prevent deterioration of the humidity resistance characteristic and ensure reliability.

However, when the thickness _Tc of the cover region is smaller than 9 mu, the thickness _Tc of the cover region is excessively thin, so that the moisture resistance is degraded regardless of the size of the grains of the cover region C and the active region A. .

In the present embodiment, the average diameter D _c of the ceramic grains in the cover region C may be smaller than the average diameter D _a of the ceramic grains in the active region A.

Grain size of the coverage area (D _c) the reason for less than the diameter (D _a) of the active region grain are as follows.

The larger the surface area of the ceramic powder, the lower the sintering temperature can occur. This is because, as the surface area of the ceramic powder becomes larger, the surface energy becomes higher and the energy is unstable as a whole, and the surface energy is lowered to move to a more stable state, which can act as a driving force of the sintering .

The internal electrodes 31 and 32 of the active area A and the ceramic layers 11 of the active area A and the margins of the ceramic layers of the active area A and the cover area C are the same when the sizes of the ceramic powder of the active area A and the ceramic powder of the cover area C are the same. The sintering may occur in the order of the first region 12, the second region 12, and the cover region C in this order. The order of the sintering is conceptual but is not absolute and may actually occur due to superposition of sintering.

The reason why the internal electrode is sintered first is that the sintering temperature of the conductive metal used as the internal electrode is lower than that of the ceramic powder.

Next, the sintering may occur in the ceramic layer 11 and the margin portion of the active region, which may cause compression stress to act on the ceramic layer between the internal electrodes due to shrinkage of the internal electrode in the sintering process of the internal electrode, It can work.

Finally, sintering may occur in the cover region (C).

Since the sintering temperature differs depending on the position as described above, the stress can be unevenly distributed in the ceramic body, and defects such as delamination and cracks can be directly induced.

In addition, it can serve as a potential risk factor for defects due to external impact (thermal shock) through the subsequent processes. The ratio of the volume ratio of the internal electrode to the thickness of the cover region is reduced in the case of an ultra-high-capacity product, and the above problem can be further exacerbated.

By reducing the particle size of the ceramic powder in the cover region (C) and lowering the sintering temperature of the cover region, it is possible to reduce the difference in sintering temperature of the active region, thereby alleviating the uneven stress distribution in the ceramic body.

As a result, by making the grain size of the cover region smaller than the grain size of the active region, it is possible to suppress the occurrence of delamination and cracking, and it is possible to improve the moisture resistance characteristic by alleviating potential factors that may cause defects even after the thermal shock is applied .

Specifically, the ratio of the diameter (D _c) compared to the diameter of the active region grain (D _a) of the cover region grain (D _a / D _c) may be 1.1 ~ 4.4.

When D _a / D _c is less than 1.1, the sizes of the ceramic powder particles used in the active area and the cover area may be similar. Therefore, there may still be non-uniformity of the stress distribution between the active region and the cover region, so that delamination and cracks may occur, and the effect of improving the moisture resistance is insignificant.

If D _a / D _c is larger than 4.4, the size of the ceramic powder particles used in the active region may be excessively larger than the size of the ceramic powder particles used in the cover region, so that the stress imbalance between the cover region and the active region may become worse. This is because the sintering of the cover region can be performed more quickly than the active region.

The average diameter (D _c , D _a ) of the ceramic grains can be measured by analyzing a cross-sectional photograph of the cover region (C) or the active region (A) extracted by a scanning electron microscope (SEM). For example, the mean diameter (D _c , D _a ) of ceramic grains can be measured using grain size measurement software that supports the standard method of measuring the average size of grain as specified in the American Society for Testing and Materials (ASTM) E112 have.

The area including at least 30 grains in the cover area and the active area can be sampled and the average diameter of the grain can be measured using the above method. Concretely, the length in the central portion and the cross-section in the thickness direction (LT section) of the triangular section of the ceramic body 10 in the width direction (W direction) are scanned by an SEM (Scanning Electron Microscope) can do.

The thickness (T _c ) of the cover region to the average diameter in the thickness direction (D _c ) of the cover region grain may be 55 or more (T _c / D _c ≥ 55). That is, the number of grains arranged in the thickness direction in the cover region may be 55 or more.

The thickness direction average diameter (D _c ) of the cover region grains can be defined as a value obtained by dividing the sum of the thickness direction diameters of the grains in the cover region by the number of grains. Concretely, the length in the central portion and the cross-section in the thickness direction (LT cross-section) of the widthwise (W direction) three-part portions of the ceramic body 10 are scanned by a scanning electron microscope (SEM) It can be measured at each of the equally spaced 10 points of the center of the triplet.

The thickness (T _c ) of the cover region may be an average value. Concretely, the length in the central portion and the cross-section in the thickness direction (LT cross-section) of the widthwise (W direction) three-part portions of the ceramic body 10 are scanned by a scanning electron microscope (SEM) The average value of the thicknesses of the cover regions measured at each of the three equally divided portions equally spaced at equal intervals from the central portion can be defined as the thickness (T _c ) of the cover region.

(T _c / D _c ) obtained by dividing the thickness (T _c ) of the cover region by the thickness direction diameter (D _c ) of the grain can be defined as the number of grains in the thickness direction of the cover region.

The greater the number of grains in the thickness direction in the cover region, the better the moisture resistance can be. Moisture penetration from the outside into the inside of the ceramic body is performed through the grain boundary rather than inside the grain. The larger the number of grains, the longer the penetration path becomes.

Another aspect of the present embodiment includes a ceramic body 10 including an internal electrode laminate portion A in which a plurality of internal electrodes are laminated; And external electrodes 21 and 22 formed outside the ceramic body 10. The thickness of the external region C of the internal electrode stacking portion A of the ceramic body 10 is preferably set to satisfy a relationship of T _c ) it was 9 ~ 25um, and the ceramic grain average diameter of the outer area (C) of the inner electrode layers of the (a) (D _c) is the average diameter (D of the ceramic grain in the inside area of the internal electrode layers of the (a) _a ) and T _c / D _c > / = 55.

The ceramic body 10 can be divided into an internal electrode laminate portion A and an external region C formed above and below the ceramic body 10 in the thickness direction. The internal electrode laminate portion A may mean a region where the internal electrodes 31 and 32 of the ceramic body 10 are laminated. The neighboring internal electrodes 31 and 32 in the internal electrode stacking portion A can be drawn out in opposite directions and electricity having the opposite polarity can be applied.

An outer region C may be formed on the upper and lower portions of the internal electrode laminate portion A. [ That is, the outer region C may be arranged in the direction of stacking the inner electrodes of the inner electrode laminate portion A.

The average diameter (D _c ) of the ceramic grains in the outer region may be an average diameter in the laminating direction.

1.1? D _a / D _c? 4.4.

The ceramic body may comprise a dielectric material.

The dielectric material may comprise barium titanate or strontium titanate.

The number of stacked internal electrodes may be 250 or more.

The internal electrode may include at least one selected from the group consisting of nickel, palladium, and alloys thereof.

The external electrode may include at least one selected from the group consisting of nickel, a nickel alloy, and palladium.

Other ceramic bodies, internal electrodes, external electrodes, etc. are the same as described above.

According to another embodiment of the present invention, there is provided a method for producing a ceramic powder, comprising the steps of: providing a first ceramic powder and a second ceramic powder having an average particle size of 1.1 to 4.4 times the average particle size of the first ceramic powder; Providing first and second ceramic green sheets using the first and second ceramic powders, respectively; Forming an internal electrode on the second ceramic green sheet; Stacking the first ceramic green sheets to form an upper cover and a lower cover having a thickness of 11 to 28 탆; Depositing a second ceramic green sheet having internal electrodes on a target number of layers to form a second ceramic green laminate; And laminating the lower cover, the second ceramic green laminate, and the lower cover.

The first ceramic powder particles may be smaller in size than the second ceramic powder particles. Specifically, the average particle diameter of the second ceramic powder particles is preferably 1.1 to 4.4 times the average particle diameter of the first ceramic powder particles.

The ratio of the grain diameter of the active region to the grain diameter of the cover region after sintering can also be adjusted in the range of 1.1 to 4.4. The diameters of the sintered first and second ceramic grains may be larger than those of the first and second ceramic powder before sintering, respectively. However, since the first and second ceramic powder particles are sintered together, .

The first ceramic powder may be used to prepare a ceramic sheet for a cover region, and the second ceramic powder may be used to prepare a ceramic sheet for an active region.

A first ceramic green sheet can be prepared by mixing a first ceramic powder with an organic solvent, a binder and the like, preparing a ceramic slurry through ball milling or the like, and using a doctor blade or the like.

A second ceramic green sheet can be produced from the second ceramic powder by the same method as described above.

The first and second ceramic powders may comprise barium titanate powder. Barium titanate has a high dielectric constant and can induce charge accumulation to realize high capacity capacitors.

On the second ceramic green sheet, a conductive paste may be printed to form an internal electrode. On the other hand, the internal electrode may not be formed on the first ceramic green sheet.

The conductive paste may include a conductive metal. Specifically, the conductive metal may include at least one selected from the group consisting of nickel, palladium, and alloys thereof.

Gold, silver, platinum, palladium and the like are expensive but stable and can be sintered in the atmosphere, but nickel and copper are inexpensive but can be oxidized during sintering, so sintering in a reducing atmosphere may be necessary.

The conductive metal may be any as long as it can impart conductivity to the internal electrode, and is not limited to the above example.

The first ceramic green sheets may be laminated to form the upper cover and the lower cover. Considering sintering shrinkage, the thickness of the upper cover and the lower cover is preferably 11 to 28 탆. As a result, the thickness of the cover region after sintering can be from 9 to 25 mu m.

The second ceramic green sheets having the internal electrodes formed thereon may be laminated to form the second ceramic green laminate. It is possible to realize a high capacity of 250 or more as the number of internal electrodes stacked. The second ceramic green laminate can form an active region later.

The bottom cover, the second ceramic green laminate and the top cover may be laminated to form the final green laminate.

The green laminate is subjected to cutting, firing, and sintering processes to produce a sintered chip. An external electrode is formed on the outside of the sintered chip with a conductive paste by a dipping method and baked to produce a multilayer ceramic electronic device.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples.

The multilayer ceramic capacitor according to the embodiment was prepared as follows.

First, in order to vary the grain size of the active region, the barium titanate powder is employed in an appropriate range within an average grain size of 0.05 to 3 mu m.

The barium titanate powder was mixed with ethanol as an organic solvent and polyvinyl butyral as a binder, followed by ball milling to prepare a ceramic slurry, and a ceramic green sheet for an active area was prepared using the ceramic slurry.

In order to vary the grain size of the cover region, the barium titanate powder was suitably used in the range of 0.05 to 3 mu m in average particle size to prepare a ceramic green sheet for a cover region.

Next, the internal electrode was printed on the ceramic sheet for the active area using a conductive paste containing nickel metal.

Next, 3 to 8 ceramic sheets for the upper cover region, 250 ceramic sheets for the active region, and 3 to 8 ceramic sheets for the lower cover region were laminated in this order, and then the green laminate was laminated at 85 kg / cm < ² > under isostatic pressing.

The pressed ceramic laminate was cut into individual chips, and the cut chips were held at 230 캜 for 60 hours in an air atmosphere to carry out the binder removal. Then, the internal electrodes were fired at 950 to 1200 ° C under an oxygen partial pressure of 10 ^-11 to 10 ^-10 atm lower than the Ni / NiO equilibrium oxygen partial pressure so that the internal electrodes were not oxidized.

After polishing the outer surface of the fired chip, the fired chip was dipped in a conductive paste for an external electrode and then baked to form an external electrode. The conductive paste for the external electrode was prepared by adding glass and a binder to the copper powder. A tin plating layer was formed on the surface of the external electrode by electroplating.

The multilayer ceramic electronic component of the comparative example was manufactured by the same method as that of the embodiment except that the average particle size of the titanic acid powder used in the cover region (T _c ), the cover region and the active region was made different.

The moisture resistance load test was performed on the ceramic capacitor manufactured by the above method, and the reliability was evaluated by measuring the insulation resistance (IR) before and after the humidity resistance load test.

The humidity resistance load test was performed for 500 (+12 / -0) hr at a rated voltage of 1.5Vr in a state of a temperature of 40 ± 2 ° C and a humidity of 90 to 95% RH, and the charge / discharge current was made 50 mA or less.

The insulation resistance (IR) was measured before and after the humidity resistance test, after heat treatment at 150 ° C (+ 0 / -10 ° C) for 1 hour and at room temperature for 24 (± 2) hours.

It was judged that the insulation resistance before the moisture resistance load test was 50 M OMEGA or more and the insulation resistance after the moisture resistance load test was 3.5 M OMEGA or more in consideration of the specifications of the product.

(T _c ) of the cover region, the ceramic grain diameter (D _c , D _a ) of the cover region and the active region, and the thickness Were measured.

Tables 1 to 5 show the case where the thickness Tc of the cover region is 6um, 9um, 15um, 25um, and 35um, respectively.

division T _c
(um) D _c
(nm) T _c / D _c D _a
(nm) D _a / D _c IR (MΩ) Invasion before After the invasion Judgment Comparative Example 1 6 60 100 66 1.1 23 1.2 Bad Comparative Example 2 6 109 55 218 2.0 32 0.6 Bad Comparative Example 3 6 120 50 528 4.4 26 1.7 Bad

division T _c
(um) D _c
(nm) T _c / D _c D _a
(nm) D _a / D _c IR (MΩ) Invasion before After the invasion Judgment Comparative Example 4 9 90 100 81 1.0 42 1.8 Bad Example 1 9 90 100 99 1.1 59 4.8 Good Example 2 9 90 100 180 2.0 72 15 Good Example 3 9 90 100 396 4.4 64 9.0 Good Comparative Example 5 9 90 100 414 4.6 36 2.1 Bad Comparative Example 6 9 164 55 147 1.0 42 1.8 Bad Example 4 9 164 55 180 1.1 58 8.4 Good Example 5 9 164 55 327 2.0 69 7.8 Good Example 6 9 164 55 720 4.4 62 10 Good Comparative Example 7 9 164 55 753 4.6 48 1.7 Bad Comparative Example 8 9 180 50 162 1.0 25 3.2 Bad Comparative Example 9 9 180 50 198 1.1 38 3.4 Bad Comparative Example 10 9 180 50 360 2.0 36 3.2 Bad Comparative Example 11 9 180 50 792 4.4 32 2.0 Bad Comparative Example 12 9 180 50 828 4.6 48 2.4 Bad

division T _c
(um) D _c
(nm) T _c / D _c D _a
(nm) D _a / D _c IR (MΩ) Invasion before After the invasion Judgment Comparative Example 13 15 150 100 135 1.0 28 3.6 Bad Example 7 15 150 100 165 1.1 53 4.6 Good Example 8 15 150 100 300 2.0 72 6.5 Good Example 9 15 150 100 660 4.4 64 6.8 Good Comparative Example 14 15 150 100 690 4.6 32 0.8 Bad Comparative Example 15 15 273 55 246 1.0 42 1.3 Bad Example 10 15 273 55 300 1.1 59 5.8 Good Example 11 15 273 55 546 2.0 79 9.2 Good Example 12 15 273 55 1200 4.4 75 9.0 Good Comparative Example 16 15 273 55 1255 4.6 53 2.1 Bad Comparative Example 17 15 300 50 270 1.0 51 1.7 Bad Comparative Example 18 15 300 50 330 1.1 23 0.6 Bad Comparative Example 19 15 300 50 600 2.0 32 1.4 Bad Comparative Example 20 15 300 50 1320 4.4 33 2.9 Bad Comparative Example 21 15 300 50 1380 4.6 40 2.1 Bad

division T _c
(um) D _c
(nm) T _c / D _c D _a
(nm) D _a / D _c IR (MΩ) Invasion before After the invasion Judgment Comparative Example 22 25 250 100 225 1.0 62 3.2 Bad Example 13 25 250 100 275 1.1 78 7.8 Good Example 14 25 250 100 500 2.0 53 3.6 Good Example 15 25 250 100 1100 4.4 68 6.2 Good Comparative Example 23 25 250 100 1150 4.6 48 2.3 Bad Comparative Example 24 25 455 55 409 1.0 52 1.4 Bad Example 16 25 455 55 500 1.1 72 7.9 Good Example 17 25 455 55 909 2.0 70 6.4 Good Example 18 25 455 55 2000 4.4 81 7.9 Good Comparative Example 25 25 455 55 2091 4.6 32 2.1 Bad Comparative Example 26 25 500 50 450 1.0 42 2.0 Bad Comparative Example 27 25 500 50 550 1.1 39 2.1 Bad Comparative Example 28 25 500 50 1000 2.0 32 0 Bad Comparative Example 29 25 500 50 2200 4.4 42 1.7 Bad Comparative Example 30 25 500 50 2300 4.6 27 0.4 Bad

division T _c
(um) D _c
(nm) T _c / D _c D _a
(nm) D _a / D _c IR (MΩ) Invasion before After the invasion Judgment Comparative Example 31 35 636 55 573 1.0 67 8.3 Good Comparative Example 32 35 636 55 700 1.1 72 7.2 Good Comparative Example 33 35 636 55 1273 2.0 72 6.9 Good Comparative Example 34 35 636 55 2800 4.4 64 7.0 Good Comparative Example 35 35 636 55 2927 4.6 67 7.0 Good Comparative Example 36 35 700 50 630 1.0 59 6.2 Good Comparative Example 37 35 700 50 770 1.1 69 7.4 Good Comparative Example 38 35 700 50 1400 2.0 74 8.0 Good Comparative Example 39 35 700 50 3080 4.4 69 6.9 Good Comparative Example 40 35 700 50 3220 4.6 75 7.5 Good

Table 1 shows a reliability evaluation result for a multilayer ceramic capacitor having a cover region thickness Tc of 6 mu.

Referring to Table 1, in Comparative Examples 1 to 3, the insulation resistance value is below the standard value and is defective regardless of the values of Tc / Dc and Da / Dc. This is because the thickness of the cover region is too thin.

Table 2 shows the reliability evaluation results of the multilayer ceramic capacitor having the cover region thickness Tc of 9 mu.

Referring to Table 2, in Examples 1 to 3, when the Tc was 9 袖 m, the Tc / Dc was 100, and the Da / Dc was 1.1, 2.0 and 4.4, the reliability was good. As a result, when Da / Dc is 1.1 to 4.4, the moisture resistance is good.

The results of Examples 4 to 6 are also similar to those of Examples 1 to 3.

In Comparative Example 4, the reliability is poor as Tc is 9 mu, Tc / Dc is 100, and Da / Dc is 1.0. This is because the grain size (Dc) of the cover region is similar to the grain size (Da) of the active region, and the effect of alleviating the uneven stress distribution due to the difference in sintering temperature between the cover region and the active region is insignificant.

Comparative Example 6 is the case where Tc is 9 袖 m, Tc / Dc is 164, and Da / Dc is 1.0, which is the same as that of Comparative Example 4.

In Comparative Example 5, the reliability was poor as Tc of 9 μm, Tc / Dc of 100, and Da / Dc of 4.6. This is because the grain size of the cover region is excessively smaller than the grain size of the active region and the cover region is sintered more quickly and the internal stress distribution is non-uniform.

Comparative Example 7 is the case of Tc of 9 um, Tc / Dc of 164, and Da / Dc of 4.6, which is the same as that of Comparative Example 5.

In Comparative Examples 8 to 12, Tc was 9 袖 m, Tc / Dc was 50, and Da / Dc was 0.9 to 4.6, all indicating poor reliability. This is because Tc / Dc is as small as 50 regardless of the value of Da / Dc. That is, Tc / Dc can mean the average number of grains in the thickness direction existing in the cover region, because the number of grains is less than 55 and the path of moisture infiltration becomes shorter.

Tables 3 and 4 show the reliability evaluation results of the multilayer ceramic capacitor having the cover region thickness Tc of 15 mu m and 25 mu m, respectively. Tables 3 and 4 show that the results are similar to those of Table 2.

Table 5 shows a reliability evaluation result for a multilayer ceramic capacitor having a cover region thickness Tc of 35 mu.

Referring to Table 5, Comparative Examples 31 to 40 show that the humidity resistance characteristic results are all good regardless of the values of Tc / Dc and Da / Dc. This is because the thickness Tc of the cover region is sufficiently thick.

The following conclusions can be drawn from the above experimental results.

First, if the thickness of the cover region is larger than 25 um, the moisture resistance is excellent.

Secondly, since the thickness of the cover region is less than 25 μm, the moisture resistance characteristic may be degraded due to non-uniformity of the stress distribution due to the sintering temperature difference between the cover region and the active region.

However, it is possible to improve the moisture resistance characteristic by making the grain size of the cover region smaller than the grain size of the active region (1.1? Da / Dc? 4.4) and adjusting the number of grains in the thickness direction of the cover region (Tc / Dc? 55) .

Third, if the thickness of the cover area is thinner than 9 μm, the moisture resistance can not be improved even if the values of Da / Dc and Tc / Dc are adjusted.

The terms used in the present invention are intended to illustrate specific embodiments and are not intended to limit the invention. The singular presentation should be understood to include plural meanings, unless the context clearly indicates otherwise.

The word 'include' or 'having' mean that there is a feature, a number, a step, an operation, an element, or a combination thereof described in the specification, and does not exclude it.

The present invention is not limited to the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims.

It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

10: Ceramic body
11: Ceramic layer
21, 22: external electrode
31, 32: internal electrode
31a: Best internal electrode
32a: lowest inner electrode
T _c : thickness of the cover area
D _c : Average diameter of the cover region grain
D _a : mean diameter of the active region grains

Claims (23)

A ceramic body;
An external electrode formed on an outer surface of the ceramic body; And
An inner electrode laminated in the ceramic body with a ceramic layer interposed therebetween;
/ RTI >
Wherein the ceramic layer comprises a first ceramic grain having _a first mean particle size (D _a ), the first ceramic grain being in physical contact with an opposing face of an adjacent internal electrode,
Wherein the ceramic body includes an active region from an uppermost inner electrode to a lowermost inner electrode and a cover region formed on an upper portion or a lower portion of the active region,
Said cover region comprising a second ceramic grain having a second average diameter (D _c )
Wherein the average diameter (D _c ) of the second ceramic grains in the cover region formed at the top or bottom is smaller than the average diameter (D _a ) of the first ceramic grains in the active region,
When called the thickness of the cover region T _c, and _{9um≤T c ≤25um, T c / D} c ≥55 the multilayer ceramic electronic device.
The method according to claim 1,
Wherein an average diameter (D _c ) of the ceramic grains in the cover region is an average diameter in the thickness direction.
The method according to claim 1,
1.1? D _a / D _c? 4.4.
The method according to claim 1,
Wherein the ceramic body comprises a dielectric material.
5. The method of claim 4,
Wherein the dielectric material comprises barium titanate or strontium titanate.
The method according to claim 1,
Wherein the number of stacked internal electrodes is 250 or more.
The method according to claim 1,
Wherein the internal electrode comprises at least one selected from the group consisting of nickel, palladium, and alloys thereof.
The method of claim 1,
Wherein the external electrode comprises at least one selected from the group consisting of nickel, a nickel alloy, and palladium.
A ceramic body including an internal electrode laminated portion in which a plurality of internal electrodes are stacked; And
And an external electrode formed outside the ceramic body,
Wherein the internal electrode laminate comprises a first ceramic grain having _a first average particle size (D _a ), the first ceramic grain being in physical contact with an adjacent inner electrode facing surface,
And a second ceramic grain having an outer region first average particle diameter (D _c ) of the internal electrode laminate portion,
(T _c ) of the outer region of the inner electrode laminate portion of the ceramic body is 9 to 25 μm, and the average diameter (D _c ) of the second ceramic grains of the outer region is less than the average diameter the average diameter of the ceramic grain (D _a) smaller than, T _c / D _c ≥55 the multilayer ceramic electronic device.
10. The method of claim 9,
Wherein the inner electrode laminate portion is drawn out in a direction opposite to that of the adjacent inner electrodes.
10. The method of claim 9,
Wherein the external region is disposed in the internal electrode stacking direction of the internal electrode stacking portion.
10. The method of claim 9,
Wherein an average diameter (D _c ) of the ceramic grains in the outer region is an average diameter in the thickness direction.
10. The method of claim 9,
1.1? D _a / D _c? 4.4.
10. The method of claim 9,
Wherein the ceramic body comprises a dielectric material.
15. The method of claim 14,
Wherein the dielectric material comprises barium titanate or strontium titanate.
10. The method of claim 9,
Wherein the number of stacked internal electrodes is 250 or more.
10. The method of claim 9,
Wherein the internal electrode comprises at least one selected from the group consisting of nickel, palladium, and alloys thereof.
10. The method of claim 9,
Wherein the external electrode comprises at least one selected from the group consisting of nickel, a nickel alloy, and palladium.
Providing a first ceramic powder and a second ceramic powder having an average particle size of 1.1 to 4.4 times an average particle size of the first ceramic powder;
Providing first and second ceramic green sheets using the first and second ceramic powders, respectively;
Forming an internal electrode on the second ceramic green sheet;
Stacking the first ceramic green sheets to form an upper cover and a lower cover having a thickness of 11 to 28 탆;
Depositing a second ceramic green sheet having internal electrodes on a target number of layers to form a second ceramic green laminate; And
Stacking the upper cover, the second ceramic green laminate and the lower cover;
/ RTI >
And the grain of the second ceramic powder is in physical contact with the opposing face of the adjacent internal electrode.
20. The method of claim 19,
Wherein the first and second ceramic powders comprise barium titanate powder in the step of preparing the first and second ceramic powders.
20. The method of claim 19,
Wherein the internal electrode is formed by printing a conductive paste in the step of forming the internal electrode.
22. The method of claim 21,
Wherein the conductive paste comprises a conductive metal.
23. The method of claim 22,
Wherein the conductive metal comprises at least one selected from the group consisting of nickel, palladium, and alloys thereof.

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